Chlorination



-., museum 11, 1929.

UNITED STATES PATEN OFFICE.

1:11am 1;. Ame; or swamrmoan, rmfnmvmu, usrenon To run '3. a. s. comm,or rmmnnnrnn, rmmsxnvmm, n- CORPORATION or DELAWARE.

' I CHLOBINATIOR.

No Drawing.

My invention relates to chlorination and particularly to bringingtogether in the vapor phase'chlorine and a substance to be. chlorinatedin such manner that explosion is 5 avoided. I v

In clorination there is great danger ofex-' f plosion when chlorinevapor is mixed-with a 4 perature if the pressure of the mixture issu'fiiciently high. Furthermore, a mixture having chlorine andhydrocarbon present in explosive proportions maybe safely handled andsafe reaction between the substancescan be efv fected by merely heatinsuch mixture in the absenee of a flame or lig t that would initiate anexplosion. It is therefore imperative to 9 avoid ignition in any part ofsuch a mixture.

However, even though a mixture of chlorine and hydrocarbon is subject tosuch conditions I of temperature and pressure that spontaneous explosionthereof is not likely to or will not '25 occur, ignition maynevertheless occur at the point where the chlorine and h drocarbonvapors are brought together, un er those other wise safe temperaturesand pressures, to produce the mixture. Moreover, ignition may occur atthe point where the chlorine and hydrocarbon are brought together eventhough'the final mixture is not of explosive proportions under theexisting temperature and pressure, although in such case explosion doesnot result'from such ignition. In other words, ignition may occur at thepoint of junction regardless of whether the resulting mixture is ofexplosive proportions at the existing temperature and pressure; Also,

there is little danger of ignition at the junction point when somesubstances are mixed with chlorine at atmospheric temperature but thereis considerable danger of ignition at the junction point when the samesubstances are so mixed at higher temperatures.

Pentaneis an example of such a substance.

I have found that when hydrocarbons are I to be mixed with, chlorine inthe vapor phase at a temperature at which the velocity of reactionbetween them is low, ignition at the junction point will not occur ifthat vapor into which the vapor is introduced is moving at sufiicientvelocity with respect to the junction point. For example, ignition willnot' occur if chlorine enters a stream of hydro- Appli'eat'ion fledFebruary 4, 1927. Serial No. 165,876

carbon vapor that is moving at a velocity in excess of one-half of thevelocity required for distinctly turbulent flow of the mixture,provldedjthe vapors are brought together at a temperature at which thevelocity of the re- .action' between themis low. This'freedom "fromdanger of ignition exists re ardless of the proportions in which the chorine and hydrocarbon arebrou ht-together and exist in thefinal mixture.ixtures consisting of chlorine and hydrocarbon in explosive proportionscan not be kept standing althou h the constituents of such mixtures maybe sa e 1y brought together by the practice of my invention. An1mportantfeature of my discovery'resides in the fact that in makingmixtures of chlorine and hydrocarbon vapors explosion due to'ignition atthe junction point is avoided both where the final mixture 1s intendedtocontain chlorine-and hydrocarbon in explosive proportion "and whenexplosive mixtures are accidentally produced during the making ofmixtures that are intendedto be in non-explosive proportions.

The velocity at which the mixture will pass with turbulent flow throughthe conduit that carries it to the reactor, may be determined in variousways. A practical method of determining that velocltv consists incooling the exterior of the con uit as by circulation of 35 water,placing a thermometer in the conduit with its bulb at the axis thereof,placing a second thermometer in the conduit with its bulb closelyadjacent the wall. of the conduit, in-

creasing the velocity of flow until the two thermometers givesubstantially the same reading. So long as the flow is not rapid enoughto produce turbulence the thermometer near the wall of the conduit willhave a lower reading, but when the velocity of turbulent flowis reachedthe resulting agitation within the conduit will cause the twothermometers to have substantially the same reading. I -Whenthe'chlorine is mixed with hydrocarbon by being introduced into thehydrocarbon vapor, ignition at the point of junction is avoided in thepractice of my invention at temperatures at which ignition wouldotherwiseoccur even though, as is very apparent, mixtures ofallproportions occur in the zone. in which the substances come together andwhile they are becoming disseminated one within the other. i

In the chlorination of substances on a commercialscale, the chlorinevapor and the substance to be chlorinated are brought together and theresultingmixture is conducted to and introduced into a reactor ind-whichthe reaction is caused to occur at a rapid'rate by conditions imposedupon the mixture in the reactor, as by the application of heat, the

conditions being so maintained that a desired substitution of chlorinetakes place'instead of an ignition. If conditions are such that themixture is delivered to the reactor vwithout substantial chlorinatingreaction in transit, thereto'therate of reaction in the mixture passingto the reactor may be said tobe low and practical handling of themixture is possible without serious danger ofignition; and furtherreferences herein to a low rate ofreaction are intended to refer to sucha safe rate'.

Thus, as a specific example of the application of my invention, it ispossible to introduce chlorine into vpentane vapor to produce a mixtureof even equal proportions. and

having a temperature of 90 C. without the occurrence of ignition at thepoint of junction provided the stream of pentane is moving in excess ofone-half of the velocity required for distinctly turbulent flow of themixture, 6. g., fifty feet per second, but ignition would occur at thattemperature at the point of junction if the pentane were not moving withthe necessary velocity even though the proportion of pentane to chlorinewere as high as 5:1, and perhaps highen Conversely, if hydrocarbon vaporis introduced into a stream of chlorine vapor, the

vapor becomes less than fifty feet per second. The velocity at which thevapor must be moving in order to prevent, in accordance with myinvention, an ignition at the junction point, depends upon the ratio ofchlorine to hydrocarbo and upon the temperature of, the resultin mixtureand that velocity must'be increased as thetempera' ture increases and asthe proportions-of the mixture approach the Iproportions of the mostexplosive mixture.

peratures below 150 C.

In practice, however, it 'is advisable to maintain a higher velocitythan is necessary for normal operation because accidental have foundthat the. velocity of reaction between vapors ofpenhugs and chlorinevapor is very low at temvariations of temperature and of proportions ofthe mixture might otherwise produce conditions requiring such highervelocity to certainly prevent ignition. The existence of a flame at thepoint where chlorine and the hydrocarbon mix causes explosionofexplosive mixtures, or, if the mixture does not ex-' plode as a resultof ignition, causes the production of products that are not desired, asdescribed in Patent No. 1,286,353. In:-the

practice of this invention the existence of such a flame 1s prevented bymaintaining such conditions with respect to the velocity of the vaporsat the time they are brought together that such a flame cannot exist orform.

A further feature of my invention is the chlorination'of substances, andparticularly saturated aliphatic hydrocarbons of three to six carbonatoms, by causing the initiation and completion of the chlorinatingreaction to occur promptly after the chlorine and substance are broughtinto contact, and thereby preventing formation of some chloride beforethe mixture comes into the influence of the reacting'agent (heat orlight) and the consequent formation of undesirable higher chloridesafter the mixture comes into the influence thereof.

What I claim and desire to secure by Letters Patent is:

1'. In the chlorination of hydrocarbons that exist in vapor phase attemperatures at which their rate of reaction with chlorine is low, thestep comprising introducing chlorine into the hydrocarbon vapor whilemaintaining the latter in motion at a velocity in excess of one-half ofthatrequired for distinct turbulent flow ofthe mixture.

2. In chlorination of hydrocarbons wherein chlorine is introduced intothe hydrocarbon, the step comprising maintaining the vapor of ahydrocarbon, that exists in vapor phase at a temperature at which itsrate of reaction with chlorine is low, in motion at'a velocitysufliciently high to prevent persistence of ignition at the point ofintroduction ing at that point.

of the chlorine under the temperature existv3'. In chlorination ofhydrocarbons, the I step com rising bringing together chlorine vapor andvapor of a hydrocarbon that exists'in vapor phase at a temperature atwhlch its-rate of reaction with chlorine is low, by maintaining oneofthe vapors in motion at a sufficient velocity, with respect to the pointat which the vapors are brought togetheryt'o prevent persistence ofignition of the mixture at that point at the existing temperature whileintroducing the other vapor into the vapor that is in motion.

4. In chlorination of hydrocarbons, the step comprising bringingtogether chlorine vapor and vapor of a hydrocarbon that exists in vaporphase at a temperature at which its rate of reaction is low, bymaintaining one of the vapors in motion at a velocity not less thanfifty feet per second in a conduit not more than eight inches indiameter with respect to the point at which the vapors are broughttogether while introducing the other vapor into the vapor that is inmotion.

5. In the chlorination of pentanes the step perature.

6. In thechlorination of pentanes the step comprising introducingchlorine vapor into pentane vapor while maintaining the pen tane vapor1n motion at a velocity in excess of fifty feet per second in a conduitnot more than eight inches in diameter with respect to the point atwhich the chlorine is introduced.

7 In the chlorination of pcntanes the step comprising introducingchlorine vapor into pentane vapor While maintaining thepentane vapor inmotion at a sufficient velocity with respect to the point at which thechlorine is introduced to prevent persistence of ignition of the mixturewhile maintaining the temperature of the mixed vapors below 8. In thechlorination of pent-anes the step comprising introducing chlorine vaporinto pentane vapor while maintaining the pentane vapor in motion at avelocityin excess of fifty feet per second in a conduit not more thaneight inches in diameter with respect to the point at which the chlorineis introduced I while maintaining the temperature of the mixed vaporsbelow 150 C.

9. In the chlorination of'hydrocarbons, the step comprising bringingtogether chlorine vapor and vapor of a hydrocarbon that exists in vaporphase at a temperature at which its rate of reaction with chlorine 1slow, by

maintaining one of the vapors in motion at a velocity in excess'ofone-half of that required for distinct turbulent flow thereof, withrespect to the point at which the vapors are brought together, whileintroducing the other'vapor into the vapor that is in motion.

10. In the chlorination of pentanes, the step comprlsmg bringingtogether chlorine taining one of the vapors in motion, with respect tothe polnt at which the vapors are brought together, at a velocity inexcess of vapor and vapor of the pentanes, by mainone-half of thatrequired for distinct turbulent flow thereof while introducing the othervapor into the vapor that is in motion. In testimony whereof, I havesigned my name to' this specification.

EUGENE ,E. AYRES, JR.

